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Chemical eor
1. Chemical EOR Progress in
China Advances and Challenges
Harry L. Chang
Harrylchang@chemortech.com
www.chemortech.com
2. Outline of Presentation
Overview
Recent advancements
Chemical EOR in China
Polymer flooding
ASP flooding
Facilities
Some controversial issues and
challenges
Summary
3. Chemical EOR Global
Status
China has most field experiences
US has focused on improvements in
chemicals, lab studies, and simulators
Increased chemical EOR mechanistic
understandings and field activities in US
and world-wide in recent years
Harry L. Chang
4. General Understanding
Polymer flooding (PF): A mature EOR process
Polymer gels: Used successfully in water shut-
off and profile modification in selected reservoirs
Surfactant-polymer (SP): Effective but expensive
ASP: Effective, less expensive, but requires
extensive treatment of injection/produced fluids
Harry L. Chang
5. Recent Advancements
Chemicals
Laboratory Studies
Simulation and Simulators
Project Design and Implementation
Facilities, Monitoring, and Evaluation
More Field Experiences
Harry L. Chang
6. EOR Chemicals
Polymers and related chemicals
Surfactants
Co-surfactants
Co-solvents
Harry L. Chang
9. Phase Behavior
Experiments
• Phase behavior experiments
– Inexpensive technique for surfactant formulation
– Measure solubalization parameters/IFT’s
– Measure coalescence/equilibration time
– Determine microemulsion viscosities
• Specific surfactant(s) can be tailored for specific oils
Harry L. Chang
10. An Excellent ME Phase Behavior
0.0 1.0 2.00.5 1.5 2.5 3.0 3.5 4.0Salinity, %: 0.75 1.25 1.75 2.25 2.75
12. High oil recovery
>90% Sorw, or Sorc<0.04
Adequate mobility control
Good surfactant/polymer transport
Low surfactant retention
Core Flooding
Harry L. Chang
13. Simulation and Simulators
Mechanistic model for core flood and
pattern simulation
Calibration and field scale simulation
Advanced simulators
Harry L. Chang
15. Daqing Oilfield
Largest polymer and ASP floods in the world
PF oil production in Daqing has been
stabilized at ~200,000 bbl/d over 10 years
Polymer requirement has doubled in last 10
years from ~80,000 t/yr to ~160,000 t/yr
Large-scale ASP floods have been
implemented since 2006
Harry L. Chang
16. Shengli Oilfield
Second largest PF in China
Also has polymer manufacturing
facilities
Several ASP pilot tests have been
conducted in the past but decided to
use SP instead
Harry L. Chang
17. PF in China Showed
Incremental recovery depends on
reservoir quality
polymer selection
polymer amount, > 500 ppm.pv now
Production of polymer and emulsions may be
expected
Large scale injection/production facilities are
necessary for successful operations
Harry L. Chang
18. Polymer Flooding also
Showed
Simplified field operations have been practiced in
field-wide operations
On-site polymer production would improve the
economics
KYPAM polymers appears to be more effective in
high perm and high salinity reservoirs
Visco-elastic behavior can reduce Sor (SPE127453)
CDG will enhance PF performance
Harry L. Chang
19. Oil Production by Polymer Flooding
Daqing Oilfield, China
0
100
200
300
400
500
600
700
800
900
1000
1993 1995 1997 1999 2001 2003 2005 2007 2009
Year
OilRatebyPolymerFlooding,mmbbls
PF Ann. Rate, mmbbls
Cum. Prod., mmbbls
22. Oil Production by Polymer Flooding
Shengli Oilfield, China
0
20
40
60
80
100
120
140
160
180
200
1997 1999 2001 2003 2005 2007 2009
Year
OilRatebyPolymerFlooding,mmbbls
PF Ann. Rate, mmbbls
Cum. Prod., mmbbls
23. KYPAM Polymers
Comb like with short branched chain to
maintain effectiveness in high salinity
brines
Wide MW range for reservoirs with
different permeabilities
Successfully applied in some reservoirs
in China
Harry L. Chang
27. ASP Floods in China
Pilot testing: Daqing, Shengli, Karamay
Large scale field projects in Daqing
Large scale injection/production facilities
have been developed in Daqing
Emulsion and scale productions were
observed
Harry L. Chang
30. ASP Results in Daqing
High incremental recovery
Severe emulsion production
Severe scale production
SP with A instead of ASP?
One of the most difficult oil for SP
flooding
Harry L. Chang
31. Karamay ASP Pilot Test Design
and Field Performance
(SPE 64726)
Process design/management: Harry
Chang
Project implementation: Karamay Oilfield
A single surfactant system using
petroleum sulfonates produced in a local
refinery
Applied the salinity gradient with STPP
for sequestration
32. ASP Pilot Test Well Pattern, 2Z-B9-3 Well Group
Karamay Oil Field (SPE 64726)
37. Some Comments on ASP
ASP requires special crude oils to improve
performances
ASP slug cost less but other costs would be
substantial (treating injection brine and
produced fluids)
Low surfactant concentration (<0.5% active)
SP formulations are available now
Some ASP projects may be just SP with A or
just P
Harry L. Chang
38. Chemical Injection Facilities
SPSW vs. SPMW injection facilities
Large-scale polymer dispersion/mixing
Large-scale ASP injection facilities
Emulsion treatment facilities
Fully automatic modular units for pilot
testing
Harry L. Chang
47. A Fully Automatic Modular Pre-Factory
Tested ASP Pilot Injection Facility
• Designed Rate: 640 m3/day
• Designed Pressure: 12 Mpa
• Chemical Processing Includes:
• Dry polymer handling, processing, & maturation
• Dry soda ash handling, processing, & dissolution
• Surfactant handling & metering
• Water conditioning chemicals (oxygen scavenger and biocide)
• Nitrogen blanket
• Automation: Allen-Bradley PLC based with full PID
Loop control for accurate chemical recipe control and
data collection
• Special Systems Included:
• R-O water softening
• Fe removal system
• Heat exchanger system for high temp fluid injection
54. SOME CONTROVERTIAL
ISSUES
Polymer dispersion
Is fully hydration on the surface necessary?
are oxygen scavenger and nitrogen blanket
necessary?
Polymer flooding vs. weak gels
ASP vs. SP
Is ASP the future?
Why SP has not been emphasized?
ASP and SP Slug Aqueous Phase
Stability/Clarity?
Harry L. Chang
55. Challenges
New polymers for high temperatures (>90o
C
Modeling polymer visco-elastic effects
Low MW polymers for low perm. reservoirs
Surfactants with low adsorption and other
additives
Low cost and effective emulsion breakers
New scale prevention technologies
Harry L. Chang
56. Summary
A large number and variety of high performance
surfactants and polymers are now available for EOR
Chemical flooding is now being used for highly
viscous crudes, under higher salinity and higher
temperature conditions
Low cost and more effective lab methods have been
developed for chemical formulations
High recovery efficiency (>90% OOIP) has been
obtained in low permeability sandstone and dolomite
reservoir cores
The amount of surfactant needed to recovery the oil
has been reduced by a factor of 2 - 5 compared to
technology used in 70’s and 80’s
57. Summary (Cont’d)
Polymer flooding has been applied in
commercial scales
ASP and SP have only been applied
successfully in pilot scales
Many challenges are still remained in the
future in chemical flooding
Large resources are available for chemical
flooding
Harry L. Chang